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/string.h> 44 #include <linux/mm.h> 45 #include <linux/socket.h> 46 #include <linux/in.h> 47 #include <linux/inet.h> 48 #include <linux/ip.h> 49 #include <linux/netdevice.h> 50 #include <linux/etherdevice.h> 51 #include <linux/skbuff.h> 52 #include <linux/errno.h> 53 #include <linux/init.h> 54 #include <linux/if_ether.h> 55 #include <net/dst.h> 56 #include <net/arp.h> 57 #include <net/sock.h> 58 #include <net/ipv6.h> 59 #include <net/ip.h> 60 #include <asm/uaccess.h> 61 #include <asm/system.h> 62 63 __setup("ether=", netdev_boot_setup); 64 65 /** 66 * eth_header - create the Ethernet header 67 * @skb: buffer to alter 68 * @dev: source device 69 * @type: Ethernet type field 70 * @daddr: destination address (NULL leave destination address) 71 * @saddr: source address (NULL use device source address) 72 * @len: packet length (<= skb->len) 73 * 74 * 75 * Set the protocol type. For a packet of type ETH_P_802_3 we put the length 76 * in here instead. It is up to the 802.2 layer to carry protocol information. 77 */ 78 int eth_header(struct sk_buff *skb, struct net_device *dev, unsigned short type, 79 void *daddr, void *saddr, unsigned len) 80 { 81 struct ethhdr *eth = (struct ethhdr *)skb_push(skb, ETH_HLEN); 82 83 if (type != ETH_P_802_3) 84 eth->h_proto = htons(type); 85 else 86 eth->h_proto = htons(len); 87 88 /* 89 * Set the source hardware address. 90 */ 91 92 if (!saddr) 93 saddr = dev->dev_addr; 94 memcpy(eth->h_source, saddr, dev->addr_len); 95 96 if (daddr) { 97 memcpy(eth->h_dest, daddr, dev->addr_len); 98 return ETH_HLEN; 99 } 100 101 /* 102 * Anyway, the loopback-device should never use this function... 103 */ 104 105 if (dev->flags & (IFF_LOOPBACK | IFF_NOARP)) { 106 memset(eth->h_dest, 0, dev->addr_len); 107 return ETH_HLEN; 108 } 109 110 return -ETH_HLEN; 111 } 112 113 /** 114 * eth_rebuild_header- rebuild the Ethernet MAC header. 115 * @skb: socket buffer to update 116 * 117 * This is called after an ARP or IPV6 ndisc it's resolution on this 118 * sk_buff. We now let protocol (ARP) fill in the other fields. 119 * 120 * This routine CANNOT use cached dst->neigh! 121 * Really, it is used only when dst->neigh is wrong. 122 */ 123 int eth_rebuild_header(struct sk_buff *skb) 124 { 125 struct ethhdr *eth = (struct ethhdr *)skb->data; 126 struct net_device *dev = skb->dev; 127 128 switch (eth->h_proto) { 129 #ifdef CONFIG_INET 130 case __constant_htons(ETH_P_IP): 131 return arp_find(eth->h_dest, skb); 132 #endif 133 default: 134 printk(KERN_DEBUG 135 "%s: unable to resolve type %X addresses.\n", 136 dev->name, (int)eth->h_proto); 137 138 memcpy(eth->h_source, dev->dev_addr, dev->addr_len); 139 break; 140 } 141 142 return 0; 143 } 144 145 /** 146 * eth_type_trans - determine the packet's protocol ID. 147 * @skb: received socket data 148 * @dev: receiving network device 149 * 150 * The rule here is that we 151 * assume 802.3 if the type field is short enough to be a length. 152 * This is normal practice and works for any 'now in use' protocol. 153 */ 154 __be16 eth_type_trans(struct sk_buff *skb, struct net_device *dev) 155 { 156 struct ethhdr *eth; 157 unsigned char *rawp; 158 159 skb->dev = dev; 160 skb_reset_mac_header(skb); 161 skb_pull(skb, ETH_HLEN); 162 eth = eth_hdr(skb); 163 164 if (is_multicast_ether_addr(eth->h_dest)) { 165 if (!compare_ether_addr(eth->h_dest, dev->broadcast)) 166 skb->pkt_type = PACKET_BROADCAST; 167 else 168 skb->pkt_type = PACKET_MULTICAST; 169 } 170 171 /* 172 * This ALLMULTI check should be redundant by 1.4 173 * so don't forget to remove it. 174 * 175 * Seems, you forgot to remove it. All silly devices 176 * seems to set IFF_PROMISC. 177 */ 178 179 else if (1 /*dev->flags&IFF_PROMISC */ ) { 180 if (unlikely(compare_ether_addr(eth->h_dest, dev->dev_addr))) 181 skb->pkt_type = PACKET_OTHERHOST; 182 } 183 184 if (ntohs(eth->h_proto) >= 1536) 185 return eth->h_proto; 186 187 rawp = skb->data; 188 189 /* 190 * This is a magic hack to spot IPX packets. Older Novell breaks 191 * the protocol design and runs IPX over 802.3 without an 802.2 LLC 192 * layer. We look for FFFF which isn't a used 802.2 SSAP/DSAP. This 193 * won't work for fault tolerant netware but does for the rest. 194 */ 195 if (*(unsigned short *)rawp == 0xFFFF) 196 return htons(ETH_P_802_3); 197 198 /* 199 * Real 802.2 LLC 200 */ 201 return htons(ETH_P_802_2); 202 } 203 EXPORT_SYMBOL(eth_type_trans); 204 205 /** 206 * eth_header_parse - extract hardware address from packet 207 * @skb: packet to extract header from 208 * @haddr: destination buffer 209 */ 210 static int eth_header_parse(struct sk_buff *skb, unsigned char *haddr) 211 { 212 struct ethhdr *eth = eth_hdr(skb); 213 memcpy(haddr, eth->h_source, ETH_ALEN); 214 return ETH_ALEN; 215 } 216 217 /** 218 * eth_header_cache - fill cache entry from neighbour 219 * @neigh: source neighbour 220 * @hh: destination cache entry 221 * Create an Ethernet header template from the neighbour. 222 */ 223 int eth_header_cache(struct neighbour *neigh, struct hh_cache *hh) 224 { 225 __be16 type = hh->hh_type; 226 struct ethhdr *eth; 227 struct net_device *dev = neigh->dev; 228 229 eth = (struct ethhdr *) 230 (((u8 *) hh->hh_data) + (HH_DATA_OFF(sizeof(*eth)))); 231 232 if (type == htons(ETH_P_802_3)) 233 return -1; 234 235 eth->h_proto = type; 236 memcpy(eth->h_source, dev->dev_addr, dev->addr_len); 237 memcpy(eth->h_dest, neigh->ha, dev->addr_len); 238 hh->hh_len = ETH_HLEN; 239 return 0; 240 } 241 242 /** 243 * eth_header_cache_update - update cache entry 244 * @hh: destination cache entry 245 * @dev: network device 246 * @haddr: new hardware address 247 * 248 * Called by Address Resolution module to notify changes in address. 249 */ 250 void eth_header_cache_update(struct hh_cache *hh, struct net_device *dev, 251 unsigned char *haddr) 252 { 253 memcpy(((u8 *) hh->hh_data) + HH_DATA_OFF(sizeof(struct ethhdr)), 254 haddr, dev->addr_len); 255 } 256 257 /** 258 * eth_mac_addr - set new Ethernet hardware address 259 * @dev: network device 260 * @p: socket address 261 * Change hardware address of device. 262 * 263 * This doesn't change hardware matching, so needs to be overridden 264 * for most real devices. 265 */ 266 static int eth_mac_addr(struct net_device *dev, void *p) 267 { 268 struct sockaddr *addr = p; 269 if (netif_running(dev)) 270 return -EBUSY; 271 memcpy(dev->dev_addr, addr->sa_data, dev->addr_len); 272 return 0; 273 } 274 275 /** 276 * eth_change_mtu - set new MTU size 277 * @dev: network device 278 * @new_mtu: new Maximum Transfer Unit 279 * 280 * Allow changing MTU size. Needs to be overridden for devices 281 * supporting jumbo frames. 282 */ 283 static int eth_change_mtu(struct net_device *dev, int new_mtu) 284 { 285 if (new_mtu < 68 || new_mtu > ETH_DATA_LEN) 286 return -EINVAL; 287 dev->mtu = new_mtu; 288 return 0; 289 } 290 291 /** 292 * ether_setup - setup Ethernet network device 293 * @dev: network device 294 * Fill in the fields of the device structure with Ethernet-generic values. 295 */ 296 void ether_setup(struct net_device *dev) 297 { 298 dev->change_mtu = eth_change_mtu; 299 dev->hard_header = eth_header; 300 dev->rebuild_header = eth_rebuild_header; 301 dev->set_mac_address = eth_mac_addr; 302 dev->hard_header_cache = eth_header_cache; 303 dev->header_cache_update= eth_header_cache_update; 304 dev->hard_header_parse = eth_header_parse; 305 306 dev->type = ARPHRD_ETHER; 307 dev->hard_header_len = ETH_HLEN; 308 dev->mtu = ETH_DATA_LEN; 309 dev->addr_len = ETH_ALEN; 310 dev->tx_queue_len = 1000; /* Ethernet wants good queues */ 311 dev->flags = IFF_BROADCAST|IFF_MULTICAST; 312 313 memset(dev->broadcast, 0xFF, ETH_ALEN); 314 315 } 316 EXPORT_SYMBOL(ether_setup); 317 318 /** 319 * alloc_etherdev - Allocates and sets up an Ethernet device 320 * @sizeof_priv: Size of additional driver-private structure to be allocated 321 * for this Ethernet device 322 * 323 * Fill in the fields of the device structure with Ethernet-generic 324 * values. Basically does everything except registering the device. 325 * 326 * Constructs a new net device, complete with a private data area of 327 * size (sizeof_priv). A 32-byte (not bit) alignment is enforced for 328 * this private data area. 329 */ 330 331 struct net_device *alloc_etherdev(int sizeof_priv) 332 { 333 return alloc_netdev(sizeof_priv, "eth%d", ether_setup); 334 } 335 EXPORT_SYMBOL(alloc_etherdev); 336