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/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 extern int __init netdev_boot_setup(char *str);
  66
  67 __setup("ether=", netdev_boot_setup);
  68
  69 /*
  70  *       Create the Ethernet MAC header for an arbitrary protocol layer
  71  *
  72  *      saddr=NULL      means use device source address
  73  *      daddr=NULL      means leave destination address (eg unresolved arp)
  74  */
  75
  76 int eth_header(struct sk_buff *skb, struct net_device *dev, unsigned short type,
  77            void *daddr, void *saddr, unsigned len)
  78 {
  79         struct ethhdr *eth = (struct ethhdr *)skb_push(skb,ETH_HLEN);
  80
  81         /*
  82          *      Set the protocol type. For a packet of type ETH_P_802_3 we put the length
  83          *      in here instead. It is up to the 802.2 layer to carry protocol information.
  84          */
  85
  86         if(type!=ETH_P_802_3)
  87                 eth->h_proto = htons(type);
  88         else
  89                 eth->h_proto = htons(len);
  90
  91         /*
  92          *      Set the source hardware address.
  93          */
  94
  95         if(saddr)
  96                 memcpy(eth->h_source,saddr,dev->addr_len);
  97         else
  98                 memcpy(eth->h_source,dev->dev_addr,dev->addr_len);
  99
 100         /*
 101          *      Anyway, the loopback-device should never use this function...
 102          */
 103
 104         if (dev->flags & (IFF_LOOPBACK|IFF_NOARP))
 105         {
 106                 memset(eth->h_dest, 0, dev->addr_len);
 107                 return ETH_HLEN;
 108         }
 109
 110         if(daddr)
 111         {
 112                 memcpy(eth->h_dest,daddr,dev->addr_len);
 113                 return ETH_HLEN;
 114         }
 115
 116         return -ETH_HLEN;
 117 }
 118
 119
 120 /*
 121  *      Rebuild the Ethernet MAC header. This is called after an ARP
 122  *      (or in future other address resolution) has completed on this
 123  *      sk_buff. We now let ARP fill in the other fields.
 124  *
 125  *      This routine CANNOT use cached dst->neigh!
 126  *      Really, it is used only when dst->neigh is wrong.
 127  */
 128
 129 int eth_rebuild_header(struct sk_buff *skb)
 130 {
 131         struct ethhdr *eth = (struct ethhdr *)skb->data;
 132         struct net_device *dev = skb->dev;
 133
 134         switch (eth->h_proto)
 135         {
 136 #ifdef CONFIG_INET
 137         case __constant_htons(ETH_P_IP):
 138                 return arp_find(eth->h_dest, skb);
 139 #endif
 140         default:
 141                 printk(KERN_DEBUG
 142                        "%s: unable to resolve type %X addresses.\n",
 143                        dev->name, (int)eth->h_proto);
 144
 145                 memcpy(eth->h_source, dev->dev_addr, dev->addr_len);
 146                 break;
 147         }
 148
 149         return 0;
 150 }
 151
 152
 153 /*
 154  *      Determine the packet's protocol ID. The rule here is that we
 155  *      assume 802.3 if the type field is short enough to be a length.
 156  *      This is normal practice and works for any 'now in use' protocol.
 157  */
 158
 159 unsigned short eth_type_trans(struct sk_buff *skb, struct net_device *dev)
 160 {
 161         struct ethhdr *eth;
 162         unsigned char *rawp;
 163
 164         skb->mac.raw=skb->data;
 165         skb_pull(skb,ETH_HLEN);
 166         eth = eth_hdr(skb);
 167         skb->input_dev = dev;
 168
 169         if(*eth->h_dest&1)
 170         {
 171                 if(memcmp(eth->h_dest,dev->broadcast, ETH_ALEN)==0)
 172                         skb->pkt_type=PACKET_BROADCAST;
 173                 else
 174                         skb->pkt_type=PACKET_MULTICAST;
 175         }
 176
 177         /*
 178          *      This ALLMULTI check should be redundant by 1.4
 179          *      so don't forget to remove it.
 180          *
 181          *      Seems, you forgot to remove it. All silly devices
 182          *      seems to set IFF_PROMISC.
 183          */
 184
 185         else if(1 /*dev->flags&IFF_PROMISC*/)
 186         {
 187                 if(memcmp(eth->h_dest,dev->dev_addr, ETH_ALEN))
 188                         skb->pkt_type=PACKET_OTHERHOST;
 189         }
 190
 191         if (ntohs(eth->h_proto) >= 1536)
 192                 return eth->h_proto;
 193
 194         rawp = skb->data;
 195
 196         /*
 197          *      This is a magic hack to spot IPX packets. Older Novell breaks
 198          *      the protocol design and runs IPX over 802.3 without an 802.2 LLC
 199          *      layer. We look for FFFF which isn't a used 802.2 SSAP/DSAP. This
 200          *      won't work for fault tolerant netware but does for the rest.
 201          */
 202         if (*(unsigned short *)rawp == 0xFFFF)
 203                 return htons(ETH_P_802_3);
 204
 205         /*
 206          *      Real 802.2 LLC
 207          */
 208         return htons(ETH_P_802_2);
 209 }
 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 int eth_header_cache(struct neighbour *neigh, struct hh_cache *hh)
 219 {
 220         unsigned short type = hh->hh_type;
 221         struct ethhdr *eth;
 222         struct net_device *dev = neigh->dev;
 223
 224         eth = (struct ethhdr*)
 225                 (((u8*)hh->hh_data) + (HH_DATA_OFF(sizeof(*eth))));
 226
 227         if (type == __constant_htons(ETH_P_802_3))
 228                 return -1;
 229
 230         eth->h_proto = type;
 231         memcpy(eth->h_source, dev->dev_addr, dev->addr_len);
 232         memcpy(eth->h_dest, neigh->ha, dev->addr_len);
 233         hh->hh_len = ETH_HLEN;
 234         return 0;
 235 }
 236
 237 /*
 238  * Called by Address Resolution module to notify changes in address.
 239  */
 240
 241 void eth_header_cache_update(struct hh_cache *hh, struct net_device *dev, unsigned char * haddr)
 242 {
 243         memcpy(((u8*)hh->hh_data) + HH_DATA_OFF(sizeof(struct ethhdr)),
 244                haddr, dev->addr_len);
 245 }
 246
 247 EXPORT_SYMBOL(eth_type_trans);
 248
 249 static int eth_mac_addr(struct net_device *dev, void *p)
 250 {
 251         struct sockaddr *addr=p;
 252         if (netif_running(dev))
 253                 return -EBUSY;
 254         memcpy(dev->dev_addr, addr->sa_data,dev->addr_len);
 255         return 0;
 256 }
 257
 258 static int eth_change_mtu(struct net_device *dev, int new_mtu)
 259 {
 260         if ((new_mtu < 68) || (new_mtu > 1500))
 261                 return -EINVAL;
 262         dev->mtu = new_mtu;
 263         return 0;
 264 }
 265
 266 /*
 267  * Fill in the fields of the device structure with ethernet-generic values.
 268  */
 269 void ether_setup(struct net_device *dev)
 270 {
 271         dev->change_mtu         = eth_change_mtu;
 272         dev->hard_header        = eth_header;
 273         dev->rebuild_header     = eth_rebuild_header;
 274         dev->set_mac_address    = eth_mac_addr;
 275         dev->hard_header_cache  = eth_header_cache;
 276         dev->header_cache_update= eth_header_cache_update;
 277         dev->hard_header_parse  = eth_header_parse;
 278
 279         dev->type               = ARPHRD_ETHER;
 280         dev->hard_header_len    = ETH_HLEN;
 281         dev->mtu                = 1500; /* eth_mtu */
 282         dev->addr_len           = ETH_ALEN;
 283         dev->tx_queue_len       = 1000; /* Ethernet wants good queues */
 284         dev->flags              = IFF_BROADCAST|IFF_MULTICAST;
 285
 286         memset(dev->broadcast,0xFF, ETH_ALEN);
 287
 288 }
 289 EXPORT_SYMBOL(ether_setup);
 290
 291 /**
 292  * alloc_etherdev - Allocates and sets up an ethernet device
 293  * @sizeof_priv: Size of additional driver-private structure to be allocated
 294  *      for this ethernet device
 295  *
 296  * Fill in the fields of the device structure with ethernet-generic
 297  * values. Basically does everything except registering the device.
 298  *
 299  * Constructs a new net device, complete with a private data area of
 300  * size @sizeof_priv.  A 32-byte (not bit) alignment is enforced for
 301  * this private data area.
 302  */
 303
 304 struct net_device *alloc_etherdev(int sizeof_priv)
 305 {
 306         return alloc_netdev(sizeof_priv, "eth%d", ether_setup);
 307 }
 308 EXPORT_SYMBOL(alloc_etherdev);