net/ethernet/eth.c

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